Partially grouted CMU construction
Based on Section 3.5 of ICC-ES AC01 and AC58, the tension and shear failure modes for post-installed anchors located in the grouted cells of a partially grouted CMU construction will follow the same design provisions as fully grouted CMU construction based on Section 3.3 of ICC-ES AC01 and AC58. However, the design in partially grouted CMU shall consider that the distance to the ungrouted cells is to be considered an edge for the purposes of design. The tension and shear failure modes for adhesive anchors located in the ungrouted cells of a partially grouted CMU construction will follow the same design provisions as ungrouted CMU construction based on Section 3.4 of ICC-ES AC58. If the location of grouted cells is unknown, follow the same design provisions as ungrouted CMU construction based on Section 3.4 of ICC-ES AC58.
Clay brick construction
The following illustrations will demonstrate how to locate the nearest adjacent head joint and how treating it as an edge will affect calculating tension breakout cones for single anchor, two anchor, and four anchor configurations. Additionally, the illustrations will demonstrate anchors installed in the face of the same CMU block, in the face of different CMU blocks( horizontally or vertically adjacent), and in the bed joints.
The following illustrations, based on the masonry anchor design provisions of ICC-ES AC01 and AC58, are intended for illustration purposes only.
Face of CMU— Single anchor and horizontal groups
Figure 1. Examples of nearest adjacent head joint for single anchor and horizontal groups
Based on Section 3.6 of ICC-ES AC58, the tension failure modes for adhesive anchors in clay brick construction are steel failure and pullout failure. The shear failure modes for adhesive anchors in clay brick construction are steel failure, anchorage failure, and brick crushing failure. The corresponding equations are provided below:
Tension— Nominal strengths
Nominal Strength Equation 1, 2 Steel Strength
N sa = A se, N ƒ uta
Pullout Strength
N k, br 1 N sa discussed on page 4. 2 N k, br shall be taken from 3rd party evaluation report such as ICC-ES ESR or IAPMO UES ER.
Shear— Nominal strengths
Nominal Strength |
Equation 1, 2 |
Steel Strength |
V sa = 0.6A se, V ƒ uta |
Anchorage Strength
V s, br
Brick Crushing V mc, br = 1750 ×
4 f ′ m A se, V
1 V sa and V mc, br discussed on pages 5-6. 2 V s, br shall be taken from 3rd party evaluation report such as ICC-ES ESR or IAPMO UES ER.
4.0 Influence of hollow head joints on CMU design
For CMU construction with hollow head joints, in addition to the ends and edges of walls, the nearest head joint on a horizontal projection from the anchor shall be treated as an edge for design purposes. The minimum distance from the nearest adjacent hollow head joint as measured from the centerline of the hollow head joint in CMU construction shall be 2 inches for adhesive anchors or the c min, HJ value for mechanical anchors, which is provided in the product installation information tables.
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